Fire suppressing composition for aerial application



United States Patent 3,196,168 SUPlRESSlNG QQMEQSITIGN FOR AERIAL APPLHCATION Kenneth E. Nelson, Phoenix, Ariz., assignor to Arizona Agrochemical Corporation No Drawing. Filed Dec. 6, 1962, Ser. No. 242,654

6 Claims. (Cl. 252--2) This application is a continuation-in-part of my copending application Serial No. 82,679, filed January 16, 1961, now abandoned.

This invention relates to a fire suppressing composition for aerial application andmore particularly to a fire suppressing composition which may be applied by various spraying methods or by aerial bombardment of forests and other areas for extinguishing and suppressing fires therein.

in the aerial application of liquid fire suppressing material, it has been recognized that fluids of low viscosity, when dropped from substantial elevations, tend to atomize and therefore cannot be relied upon to land with sufficient concentration on specific target areas. It has been found that liquid fire suppressing material having high viscosity, when dropped from substantial elevations, tend to hold together, so that these liquids can be confined to a specific target area and will descend thereupon with sufiicient concentration to be effective.

Prior art fire suppressing compositions have lacked sufficient viscosity for use in coating fiora with a sufficiently thick layer of fire suppressing chemicals to provide ample protection for various materials which may furnish fuel to a fire. As for example, fire suppressing compositions which are sprayed onto shrubbery and trees adjacent a dwelling, require a considerable amount of fire suppressing chemicals in order to Withstand or ward off combustion when subjected to sparks or minor cornbustion which might start a major fire.

Additionally, it has been found that most thickening agents for increasing the viscosity of the liquid fire suppressing materials are not compatible with the most effective fire suppressing chemicals available. Furthermore, many of the fire suppressing chemicals which are compatible with some thickeners have such a low fire suppressing capacity that great amounts of these fire suppressing materials rnust be employed when used with certain compatible thickeners. Thus, such combinations create a pay load which is not feasible for aerial application, or create a combination of elements which is excessively expensive from a material standpoint.

Many experiments have been made with highly viscous water, including gelatinous additives, however, these gelatinous additives are not compatible with the most effective fire suppressing materials which have electrolytic character. Furthermore, many of the fire suppressing materials used are effective when wet but have little or no fire suppressing character when dry.

Previous to the present invention, it has not been possible to obtain a composition which comprises economical elements, including an effective fire suppressing material of the electrolytic type and a compatible thickener or viscous agent which will permit accurate and concentrated application, by aerial means, to a specific target area.

Accordingly, it is an object of the invention to provide a fire suppressing composition, for aerial application, comprising economical elements which include an effective fire suppressing character and a compatible thickening character in order to permit accurate and concentrated aerial application of the composition which later is efiective in suppressing fire, either when wet or after the composition has dried upon foliage and grass, or the like.

Another object of the invention is to provide a fire suppressing composition for aerial application which per- Bdfifidfifi Patented July 20, 1965 mits the accurate treatment of strategic areas in order to reduce the fire hazard therein and to protect valuable property adjacent to a potential fire hazard.

Another object of the invention is to provide a fire suppressing composition which may readily be applied to certain areas for the prevention or the spread of fires through or around areas for a considerable time after the composition has been applied.

Another object of the invention is to provide a fire suppressing composition which may readily be applied to extinguish existing fires by direct application onto the burning areas.

Another object of the invention is to provide a fire suppressing composition for aerial application comprising specific electrolytic-type fire suppressing elements in combination with another very compatible element which attains a highly viscous condition of a water vehicle in the composition.

Another object of the invention is to provide a composition wherein a thickening agent, such as a colloidal grade of attapulgus type clay, is very compatible with an aqueous solution of such electrolyte materials as diannnonium phosphate, mono-ammonium phosphate, ammonium chloride, or ammonium sulfate, all of which are economical and very effective fire suppressing materials.

Another object of the invention is to provide a fire suppressin' composition for aerial application which is very elfective in proportion to the pay load of an airplane and which is also very economical with respect to the initial cost of the materials.

Another object of the invention is to provide a fire suppressing composition for aerial application which has a highly viscous aqueous character, a compatible and elec trolyte fire suppressing material which, when applied, effectively retards fire and later, may be very beneficial to plants, grass, and/or shrubbery in the area of the application.

A further object of the invention is to provide a fire suppressing composition for aerial application wherein fluorescent illuminating or coloring material is effective to cause target areas on which the composition has been applied to be readily discernible to pilots who are progressively applying loads of the composition during either day or night to grass, plants, or shrubbery on the ground.

Another object of the present invention is to provide a fire suppressing composition employing an attapulgite type clay which provides a highly viscous vehicle for fire suppressing chemicals whereby the composition, when sprayed or dropped on fiora or foliage, provides for a thick coating of the materials on such foliage or flora, thereby holding a substantial amount of fire suppressing chemicals to the fiora and foliage in order to provide very substantial fire protection.

Further objects and advantages of the invention may be apparent from the following specification and appended claims.

Generally, the fire suppressin composition for aerial application includes:

(1) One or more fire suppressing chemicals, either singly or in combination with each other, including inorganic bases, inorganic acids, salts of inorganic acids, and heat labile organic acid amides or salts, hereinafter referred to as soluble fire retarding and suppressing materials.

(2) A thickening agent comprising a colloidal attapulgite type clay having adhesive or sticking character.

(3) A fluorescent, illuminatinv or coloring agent.

(4) A corrosion inhibitor.

(5) Suificient water to provide a desired viscosity and adhesive or sticking character, of the composition.

(6) Halogenated hydrocarbons known to have fire sup- 3 pressing character, such as that of carbon tetrachloride.

Element number one, above, may include various materials, such as ammonium sulfate, di-ammonium phos phate, mono-ammonium phosphate, sulfamic acid, phosphoric acid, or urea, ammonium chloride, or the like. These materials have low mammalian toxicity, all have good fire suppressing character, and are quite economical from the standpoint of initial cost. Furthermore, these materials are economical to apply since nominal amounts of them are required in an aqueous solution to obtain effective fire control and/or extinction. Additionally, it will be appreciated that the effectiveness of the attapulgus type colloidal grade clay, as a thickening agent, is also favorable since nominal amounts of this type of thickening agent are required in the composition to provide surfcient viscosity thereof so that it may be aerially applied to specific target areas with high concentration.

It has been found that sodium phosphates, including sodium tri-polyphosphate, tetra-sodium pyrophosphate, sodium hexametaphosphate, tri-sodium phosphate, or similar materials, when added to the composition of the present invention, cause said composition, when dry, to become a hard tough film which has a tenacious ability to stay on flora or other fuel materials.

The thickening agent of the colloidal attapulgite type clay is very compatible with the aqueous solutions of the electrolytic type fire suppressing materials, hereinabove set forth.

Fluorescent material or coloring agents utilized in the composition of the present invention act to identify or color the areas on which the composition has been applied so that subsequent applications to adjacent areas permit a pilot to form a continuous firebreak with great precision.

Corrosion inhibitors in the composition are used to neutralize any corrosive character of the fire suppressing materials. As for example, some of these materials may be slightly corrosive to the mixing and application equipment of aerial transport tanks, and for this reason, the corrosion inhibitor is utilized.

The composition of the present invention may be prepared by customary methods known to those skilled in the art. In most cases, simple mixing or blending of the dry materials in desired proportions may be accomplished. These materials are then added to a desired amount of water and further mixed until a fluid composition occurs. Said further mixing is preferably accomplished by high shear action, such as may be afforded by a Waring Blendor which operates at high speed to shear the clay materials and thereby the molecules of these materials are rearranged and in this condition, attain a highly viscous character of the clay and water vehicle in which the fire suppressing materials are then suspended. Alternatively, such further mixing may be accomplished by the impellers of high speed recirculating pumps which may be coupled to equipment used for field mixing and/ or application of the composition of the present invention.

Another method used in such further mixing may be accomplished by rotating a bladed high speed impeller disc or circular saw-type structure in a slurry of the composition when contained in a tank.

The relative proportions of the respective ingredients of the present composition may vary over a considerable range without seriously impairing effectiveness. However, for best and most economical results, it is desirable to select optimum proportions which are influenced to a certain extent by the ingredients used, the methods of application, and the desired results.

While representative formulas are set forth in the following examples, it will be understood that these specific examples are representative of some preferred compositions of the present invention and that proportions of the materials contained therein may vary in accordance with the following ranges of percentage related by weight to a slurry condition of the overall mixed composition.

EXAMPLE 1 Low, Prc- High, percent ierred, percent percent Ammonium Sulfate 5 18 35 Colloidal grade attapulgite type clay 4 7 A Fluorescent, Illuminating or Coloring Agent .25 .5 1 Corrosion Inhibitor 05 1 5 Water 48. 5 74. 4 90. 65

EXAMPLE 2 Mono-Ammonium. Phosphate. 5 18 35 Colloidal grade Attapulgite type Clay 4 7 15 A Fluorescent, Illuminating or Coloring Agent 5 1 Corrosion Inl1ibitor .05 1 .5 Water 48. 5 74 4 90. G5

EXAMPLE 3 Di-Ammoniun1 Phosphate 5 18 Colloidal grade Attapulgite type Clay 4 7 15 A Fluorescent, Illuminating or Coloring Agent 25 5 1 Corrosion Inhibitor--. .05 1 .5 Water 48. 5 74 4 90.65

EXAMPLE 4 Ammonium Sulfate 5 18 35 Colloidal grade Attapulgite type Clay 4 7 15 A Fluorescent, Illuminating or Coloring Agent 25 5 1 Corrosion Inhibitor- 05 1 5 Sodium Phosphate 25 l 2. 25 Water 48. 25 73 4 90.

EXAMPLE 5 Ammonium Sulphate 5 14 3o Colloidal grade Attapulgite type Clay 4 8. 25 15 A Fluorescent, Illuminating or Coloring EXAMPLE 6 Ammonium Sulphate 5 13. 25 30 Colloidal grade Attapulgite type Clay 4 7. 5 15 Urea 5 2. 5 1O Tetra-Sodium Pyrophosphate 25 1.25 10 A Fluorescent, Illuminating or Coloring 2 EXAMPLE 7 Ammonium Chloride 5 18 30 Colloidal grade Attapulgite type Clay 4 7 15 Corrosion Inhibitor O5 1 5 A Fluorescent, Illuminating or Coloring Agent 25 5 1 Water 53. 5 74. 4 90. 7

The attapulgite clay employed in the compositions of Example 1-7 was a commercially available material designated Minugel 200 and AA Special. These clays are preferred in the pactice of the present invention.

It will be noted that the maximum amount oflire retardant salt, in the present composition, is determined by its solubility to saturation in Water, while its minimum amount is determined by desired fire retardant effectiveness such as that which will extinguish or prevent the spread of a fire. Further, it will be noted that the optimum amount of attapulgite clay may depend upon the efficiency of the mixing apparatus or method used, since the greater efficiency of mixing tends to permit a relative decrease in the amount of the clay required to provide the desired viscosity of the composition.

The maximum amount of clay which can be used in the composition may be determined by the ability of the spraying or applying apparatus to function with the material of high viscosity. For example, conventional spraying equipment will be unable to project material which has a viscous character which is too thick to handle, whereas material of high viscosity may be dropped from equipment in an airplane. A minimum amount of the clay may be determined by the amount of the fire suppressing materials to be coated onto flora or other combustible materials.

It will be obvious that the optimum amount of corrosion inhibitor may be determined by the corrosive character of the remaining chemicals of the composition and more particularly including the chemical salts of the fire suppressing materials in the composition.

Optimum amounts of the coloring materials and hue thereof may depend upon the subjects on which the fire suppressing composition of the invention may be applied.

According to the present invention, viscosity of any of the foregoing compositions may be greatly enhanced by the addition of calcium oxide (unslaked lime) or calcium hydroxide. An amount of calcium oxide or calcium hydroxide, equal to about 1% to 10% of the foregoing compositions, including the water, may be added thereto in order to greatly increase the viscosity thereof. The calcium oxide or calcium hydroxide is added to the water in the foregoing compositions and then mixed with the other ingredients.

Urea, in the present compositions, serves to enhance the hardness and toughness of the compositions when dried on flora or fuel and also enhances the fire retardant and fire suppressing character of the composition.

It will be understood that water may be added to the fire suppressing material in sufficient amounts to bring it into an aqueous solution, and then carbon tetrachloride or a similar halogenated hydrocarbon to complete the requirement for a fluid vehicle to attain the desired consistency of the composition. The carbon tetrachloride acts as a dual purpose material and will thus supply fluidity to the composition and will also enhance the re suppressing effectiveness thereof.

An example of the foregoing attapulgite colloidal grade clay is as follows:

Chemical analysis SiO (as silica) 8.61%. SiO (hydrated) 1.74%.

Si (combined with bases 46.52%. A1 0 12.01%. MgO 7.12%. Se FO 3.21%. FeO 22%. TiO 49%. Mn0 08%. Cat) 1.18%. Na O 11%. K 0 51%. P 0 55%. Total ignition loss 17.30%. Refractive index:

Alpha 1.506 to 1.522. Gamma 1.530 to 1.540.

Bi-refringence .021 to .032. Optical character Negative. H ar d n e s s (approximately) 2.0 (on Mohs scale). Base exchange capacity to milliequivalents per 100 grams (in distilled water).

pH 7.3 to 8.2. Specific gravity 2.2 to 2.4.

The coloring agent in the above examples may be red iron oxide or ultramarine blue. A suitable illuminating or flourescent material known to those skilled in the art may be used for night application to lend target identity to the composition.

The corrosion inhibitor, set forth in the above examples, may include sodium silico fluoride, sodium dichromate, potassium dichromate, chromic acid, sodium thiosulphate, or other effective materials.

The foregoing composition may be applied by spraying to grass, plants, and shrubbery from nearly ground level, if desired, to provide a protective coating thereon which will last for a considerable time, as for example, several months during the fire season. This coating on grass, plants, and shrubs, when applied to areas surrounding a home or other valuable property, for example, will protect such property against the invasion of a fire from an adjacent area.

When the composition of the invention is applied by aerial means, such as an aircraft tanker, the liquid of the composition is dropped from a considerable elevation and due to its viscosity, it does not vaporize but drops in high concentration in a specific area of the target. These target areas may be successively covered in overlapping relationship in order to provide a firebreak through a forest, for example. 7

Additionally, the composition may be similarly applied directly to an area in which a fire exists in order to extinguish the fire. If a firebreak is provided by application of the present composition, it may be in existence for a considerable period of time in anticipation of a fire reaching the area of the firebreak.

During application of the composition, the Water therein is held and retained on the surfaces of grass, plants, and shrubbery, and from a standpoint of immediate fire protection, is very effective. When the composition dries, the coating formed by the colloidal grade of attapulgite type clay, together with the electrolyte fire suppressing material retained therein is very effective in the prevention of fire.

it will he appreciated by those skilled in the art that various modifications of the present invention may be resorted to in a manner limited only by a just interpretation of the following claims.

I claim:

11. A fire suppressing composition consisting essentially of (a) an electrolytic fire suppressing salt having low mammalian and plant toxicity selected from the class consisting of ammonium sulfate, ammonium chloride, mono-ammonium phosphate and di-ammonium phosphate; and

(b) colloidal attapulgite clay;

said composition being substantially dry and having a weight ratio of salt to clay of from 5:15 to :4.

2. A fire suppressing composition consisting essentially of (a) an electrolytic fire suppressing salt having low mammalian and plant toxicity selected from the class consisting of ammonium sulfate, ammonium chloride, mono-ammonium phosphate and di-ammo-nium phosphate; and

(b) colloidal attapu-lgite clay;

(c) a corrosion inhibitor selected from the class consisting of sodium silicofluoride, sodium dichromate, potassium dichromate, chromic acid and sodium thiosulfate in an amount sufficient to inhibit the corrosive action of said salt upon mixing and application equipment; and

(d) a coloring agent selected from the class consisting of red iron oxide and ultraman'ne blue;

said composition being substantially dry and having a weight ratio of salt to clay of from 5: 15 to 35:4.

3. The fire suppressing composition of Claim 2 wherein said salt is ammonium sulfate.

4. The method of fighting and suppressing fires in forests, shrubbery, and grass comprising coating flora therein with a composition consisting essentially of:

(a) an electrolytic fire suppressing salt having low mammalian and plant toxicity selected from the class consisting of ammonium sulfate, ammonium chloride, mono-ammonium phosphate and (ii-ammonium phosphate; and

( b) colloidal attapulgite clay;

said composition being substantially dry and having a weight ratio of salt to clay of from :15 to 35:4.

5. The method of fighting and suppressing fires in forests, shrubbery, and grass comprising:

(a) mixing a composition consisting essentially of (i) an electrolytic fire suppressing salt having low mammalian and plant toxicity selected from the class consisting of ammonium sulfate, ammonium chloirde, mono-ammonium phosphate and di-ammonium phosphate, and

(ii) colloidal .attapulgite clay under high shear conditions with Water in an amount sutficient to attain a viscous dispersion thereof, said mixing thereby rendering said composition especially adapted to aerial application;

('b) aerially applying said viscous dispersion to said forests, shrubbery, and grass in an amount sufficient to form a fire suppressing coating thereon, said composition having a weight ratio of salt to clay of from 5:15 to 35:4.

6. The process of preparing a fire suppressing composition adapted to aerial application comprising:

(a) intimately dry mixing an electrolytic fire suppressing salt having low mammalian and plant toxicity selected from the class consisting of ammonium sulfate, ammonium. chloride, mono-ammonium phasphate and di-ammonium phosphate with colloidal attapulgite clay, the Weight ratio of salt to clay in the mixture being from 5: 15 to 35:4; and

5 (b) thereafter further mixing the dry-mixed salt and clay under high shear conditions with water in an amount suilicient to produce a viscous dispersion.

References Cited by the Examiner UNITED STATES PATENTS 1,910,653 5/33 Thomas et a1 252-387 XR 1,997,669 4/35 Arcieri l692 2,044,758 6/36 Cross et al. 2528.5 XR 2,551,919 5/51 Williamson et al 2522 XR 2,964,468 12/60 De Bonna 252--2 XR 3,079,333 2/63 Malone et al 252-85 FOREIGN PATENTS 545,514 5/42 Great Britain.

OTHER REFERENCES Chemical Week Article, Chemical Week, vol. 89, No. 14, October 7, 1961, pages 39-40.

Composition and Properties of Oil Well Drilling Fluids, Rogers, Gulf Pub. Co., Houston, 1953 (pages The Use of Chemicals in Forest Fire Control, US. Department of Agriculture, Forest Service, Forest Product Laboratory, Madison 5, Wisconsin, No. 1199, March 1956. Table 1 after page 11.

JULIUS GREENWALD, Primary Examiner. 

1. A FIRE SUPPRESSING COMPOSITION CONSISTING ESSENTIALLY OF (A) AN ELECTROLYTIC FIRE SUPPRESSING SALT HAVING LOW MAMMALIAN AND PLANT TOXICITY SELECTED FROM THE CLASS CONSISTING OF AMMONIUM SULFATE, AM MONIUM CHLORIDE, MONO-AMMONIUM PHOSPHATE AND DI-AMMONIUM PHOSPHATE; AND (B) COLLOIDAL ATTAPULGITE CLAY; SAID COMPOSITION BEING SUBSTANTIALLY DRY AND HAVING A WEIGHT RATIO OF SALT TO CLAY OF FROM 5:15 TO 35:4. 